Sodium Thiosulphate (Na2S2O3)

This is our most popular Sodium Thiosulphate (Na2S2O3) – Sodium Thiosulphate Pentahydrate

Sodium Thiosulphate Pentahydrate



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Need Sodium Thiosulphate Pentahydrate?

  • We supply sodium pentahydrate in 1kg containers, with discounts available for bulk orders over 4 items
  • We also supply sodium thiosulphate 0.1M and 0.01M
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How is Sodium Thiosulphate Used to Treat Water?

This compound can be used to dechlorinate water, such as in swimming pools, spas and aquaria, reducing the concentration of chlorine. The same process can also be used in water treatment plants to clean backwash water before it’s released back to rivers.


Sodium Thiosulphate Can Be Used to Test Bleach

Sodium thiosulphate is used during pH tests conducted in bleach products. This compound can neutralise the colour-removing properties of bleach, allowing the pH tests to be conducted using common pH indicators. The reaction involves reduction of bleach’s active ingredient hypochlorite, with thiosulphate being oxidised to sulphate.

4 NaClO Na2S2O3 2 NaOH → 4 NaCl 2 Na2SO4 H2O


Uses of Sodium Thiosulphate in the Lab

This compound also reacts with bromine, removing free ions from solution. For this reason, sodium thiosulphate is commonly used in chemistry labs to ensure safe disposal of bromine-containing solutions. It also works with iodine and many other strong oxidisers.


Chemical Reactions Involving Sodium Thiosulphate

At temperatures above 300 degree Celsius, sodium thiosulphate can decompose to sodium sulphate and sodium polysulphide.

4 Na2S2O3 → 3 Na2SO4 Na2S5

Typically, most thiosulphate salts also decompose in the presence of acids. Even in the presence of weak acids, sodium thiosulphate is decomposed to sulphur dioxide, sulphur and water. This is known as a clock reaction: as the sulphur reaches a certain concentration, the solution goes from colourless to yellow. It’s typically used to show rate of reaction in chemistry school labs.

Na2S2O3 2 HCl → 2 NaCl S SO2 H2O


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MSDS Files

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Looking to Buy Sodium Thiosulphate?

Buy sodium hydroxide solution from ReAgent, a leading UK chemical manufacturer. We supply sodium thiosulphate in 1kg containers with discounts available on bulk orders. ReAgent also supplies sodium thiosulfate in 0.01M and 0.1M solutions. All of our products come with a 100% quality guarantee, with further options available for specific pack sizes or custom labelling.

About Sodium Thiosulphate

Sodium thiosulphate (Na2S2O3) is an inorganic compound typically available in a highly hydrated form. Also spelled as thiosulfate, it dissolves easily in water but not in alcohol. Sodium thiosulfate decomposes when heated, releasing toxic gases like disodium oxide and sulphur oxide. At the risk of explosion, it should be stored carefully, away from oxidising agents like potassium permanganate, nitrate or chlorate.

How is Sodium Thiosulfate Produced?

In the industry, sodium thiosulphate is synthesised from by-products of sodium sulphide production. This solution, containing sodium carbonate, is mixed with sulphur dioxide and subsequently re-crystallised. Another possible method involves boiling sodium polysulphide and nitro compounds, followed by several steps of concentration and purification of sodium thiosulphate. In the lab, this chemical can be produced from sodium sulphide heated in the presence of sulphur or, alternatively, by boiling sulphur and sodium hydroxide.

First Aid Measures

In case of contact with skin or eyes, wash affected area with copious amounts of water and remove all contaminated clothing. In case of ingestion, rinse mouth and seek medical advice. As a safety precaution, always wear appropriate protective clothing, including gloves and goggles.

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All our products come with 100% quality guarantee and are usually dispatched within 24 hours after purchase. If you need assistance, a member of staff will be glad to help before, during and after your order. Simply contact us for further information or free technical advice. We offer a wide range of products, from petrochemicals to pharmaceuticals, including bespoke solutions to suit your needs.
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